使用Redis实现限流
- 原理：使用Redis的Hash数据结构，把对应的key、接口url、限流规则存放进redis，在拦截器中对接口进行拦截，获取到有配置的url，进行规则获取，获取到规则之后，对redis对应接口对应key进行increment自增的操作(increment 指令是线程安全的，不用担心并发的问题),如果是第一次的话,设置该key的过期时间，过期时间为配置时间，单位为配置单位，下次调用的时候，如果当前接口对应key的自增数大于配置的limit数则进行请求超出限制的提示。
-
具体步骤
- 引入Redis依赖包,和其他工具包
<!-- 阿里json -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.41</version>
</dependency>
<!-- 整合Redis start -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<!-- 整合Redis end -->
- 在yml文件中编写限流接口和限流规则
request_limit:
# 限流的接口
url: /utils/redis,/demo/user/account
rules:
# 限流规则，每秒3次调用
limit: 3
time: 1
timeUnit: SECONDS
- 编写限流配置类
public class RequestLimitConfig implements Serializable {
private static final long serialVersionUID = 1101875328323558092L;
// 最大请求次数
private long limit;
// 时间
private long time;
// 时间单位
private TimeUnit timeUnit;
public RequestLimitConfig() {
super();
}
public RequestLimitConfig(long limit, long time, TimeUnit timeUnit) {
super();
this.limit = limit;
this.time = time;
this.timeUnit = timeUnit;
}
public long getLimit() {
return limit;
}
public void setLimit(long limit) {
this.limit = limit;
}
public long getTime() {
return time;
}
public void setTime(long time) {
this.time = time;
}
public TimeUnit getTimeUnit() {
return timeUnit;
}
public void setTimeUnit(TimeUnit timeUnit) {
this.timeUnit = timeUnit;
}
@Override
public String toString() {
return "RequestLimitConfig [limit=" + limit + ", time=" + time + ", timeUnit=" + timeUnit + "]";
}
}
- 继承
HandlerInterceptorAdapter类,实现其方法编写限流拦截器
import com.alibaba.fastjson.JSONObject;
import com.example.demo.config.RequestLimitConfig;
import com.example.demo.constants.GlobalConstants;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.MediaType;
import org.springframework.util.StringUtils;
import java.nio.charset.StandardCharsets;
/**
* 接口限流拦截器
*/
public class RequestLimitInterceptor extends HandlerInterceptorAdapter {
private static final Logger log = LoggerFactory.getLogger(RequestLimitInterceptor.class);
@Autowired
private RedisTemplate redisTemplate;
/**
* 在方法被调用前执行。在该方法中可以做类似校验的功能。如果返回true，则继续调用下一个拦截器
*
* @param request
* @param response
* @param handler
* @return
* @throws Exception
*/
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
/**
* 获取到请求的URI
*/
String contentPath = request.getContextPath();
String uri = request.getRequestURI();
if (!StringUtils.isEmpty(contentPath) && !contentPath.equals("/")) {
uri = uri.substring(uri.indexOf(contentPath) + contentPath.length());
}
log.info("uri={}", uri);
/**
* 尝试从hash中读取得到当前接口的限流配置
*/
String str = this.redisTemplate.opsForHash().get(GlobalConstants.REQUEST_LIMIT_CONFIG, uri).toString();
RequestLimitConfig requestLimitConfig = JSONObject.parseObject(str, RequestLimitConfig.class);
if (requestLimitConfig == null) {
log.info("该uri={}没有限流配置", uri);
return true;
}
String limitKey = GlobalConstants.REQUEST_LIMIT + ":" + uri;
/**
* 当前接口的访问次数 +1 increment 指令是线程安全的，不用担心并发的问题
*/
long count = this.redisTemplate.opsForValue().increment(limitKey);
if (count == 1) {
/**
* 第一次请求，设置key的过期时间
*/
this.redisTemplate.expire(limitKey, requestLimitConfig.getTime(), requestLimitConfig.getTimeUnit());
log.info("设置过期时间：time={}, timeUnit={}", requestLimitConfig.getTime(), requestLimitConfig.getTimeUnit());
}
log.info("请求限制。limit={}, count={}", requestLimitConfig.getLimit(), count);
if (count > requestLimitConfig.getLimit()) {
/**
* 限定时间内，请求超出限制，响应客户端错误信息。
*/
response.setContentType(MediaType.TEXT_PLAIN_VALUE);
response.setCharacterEncoding(StandardCharsets.UTF_8.name());
response.getWriter().write("服务器繁忙，稍后再试");
return false;
}
return true;
}
/**
* 在方法执行后调用(暂未使用)
*
* @param request
* @param response
* @param handler
* @param modelAndView
* @throws Exception
*/
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
super.postHandle(request, response, handler, modelAndView);
}
}
- 实现
WebMvcConfigurer接口,编写资源配置类
/**
* 资源配置器
*/
@Configuration
public class WebMvcConfiguration implements WebMvcConfigurer {
@Value("${request_limit.url}")
private String url;
// 添加拦截器
@Override
public void addInterceptors(InterceptorRegistry registry) {
// 添加限流的接口
registry.addInterceptor(this.requestLimitInterceptor())
.addPathPatterns(url.split(","));
}
@Bean
public RequestLimitInterceptor requestLimitInterceptor() {
return new RequestLimitInterceptor();
}
}
- 编写服务启动时注入限流接口和规则
import com.alibaba.fastjson.JSONObject;
import com.example.demo.constants.GlobalConstants;
import com.example.demo.exception.BusinessException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Component;
/**
* 初始化运行方法
*/
@Component
public class ApplicationRunnerImpl implements ApplicationRunner {
private static final Logger log = LoggerFactory.getLogger(ApplicationRunnerImpl.class);
// 引入redis
@Autowired
private RedisTemplate redisTemplate;
@Value("${request_limit.url}")
private String url;
@Value("${request_limit.rules.limit}")
private String limit;
@Value("${request_limit.rules.time}")
private String time;
@Value("${request_limit.rules.timeUnit}")
private String timeUnit;
@Override
public void run(ApplicationArguments args) throws Exception {
// 已经写好了方法
//TestCron.init();
JSONObject rulesJson = new JSONObject();
rulesJson.put("limit", limit);
rulesJson.put("time", time);
rulesJson.put("timeUnit", timeUnit);
try {
String[] urlArr = url.split(",");
// 初始化在Redis中存入接口限流规则
for (String item : urlArr) {
redisTemplate.opsForHash().put(GlobalConstants.REQUEST_LIMIT_CONFIG, item, rulesJson);
log.info("Redis存放成功,接口地址:" + item + " 限流规则:" + " 时间:" + time + " 单位:" + timeUnit + " 次数:" + limit);
}
} catch (Exception e) {
e.printStackTrace();
throw new BusinessException("限流规则配置错误,请使用逗号分割");
}
}
}
- Controller接口写入配置的路径即可
- 进行请求,快速刷新浏览器，结果如图
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